Slot cleaner for motion-picture machines



May 17, 1927. 1,629,152

1... DE FOREST SLOT CLEANER FOR MOTION PICTURE MACHINES Original Filed April 28, 1925 avwamtoz #MM flame/1 8 1 Patented May 17,1927.

,uniTED STATE-S PATENT OFFICE.

LEE De FOREST, or NEW YORK, n. Y., Assronon T 1m ronnsr PHONOFILM CORPORA- rron, or NEW YORK, N. Y., A conroimrron or DELAWARE.

SLOT CLEANER FOB MOTION-PICTURE MACHINES.

Original application filed April 28,1923, Serial No. 635,831. I Divided and this application filed December This appii'cation is a division of my application berial No. 635,331, filed April 28,

The invention relates to means for clean- 5 ing light slots in motion picture machines for recording and reproducing sound such as a projector or camera, which is simple and eflicient in operation and economic in manufacture.

The further object of the invention is to provide means which will permit of the cleaning of the light slot in motion picture apparatus for recording and reproducing sound which may be operated during the operation of such apparatus.

Further objects of the invention will. appear more fully hereinafter.

-' The invention consists substantially in the construction, combination, location and relative arrangement of parts, all as will be more fully hereinafter set forth, as shown by the accompanying drawing and finally pointed out in the appended claims.

Referring to the drawing: 7

Figure 1 shows diagrammatically in elevation of a structure section of a light slot or slit such as is commonly embodied in motion picture apparatus adapted to record and reproduce sound. a

Fig. 2 is the same view, showing a light slot constructed in accordance with the; principles of my invention.

The same part is designated by the same reference character wherever it occurs throughout the several views.

In the practical operation of motion pic ture machines, such as projectors or cameras, and especially in such types of machine which are employed for photographic sound waves, it is customary for the light from the source thereof to pass through whatis termed in the art a light slot or slit past which the film is moved. Due to the tart that this slot or slit must of necessity be 4 of extremely small size, especially in the talking moving picture art, and the further fact that the film in its transit through the machine picks up and carries therewith fine dust specks and other extraneous material. one source of difiiculty has been that the light slot or slit has become clogged thereby impairing the efiicien'cy of the machine in the motion picture photography art, caus- Serial No. 757,115.

ing the detector imperfect recording or reproduction, etc.

It is the special purpose of my present invention to provide a simple and efficient arrangements modifying the principles of my invention, I wish it to be understood that I do not wish it to be limited or restricted thereto as many other arrangements will readily occur to those skilled in the art without departing from the spirit and scope of my invention as defined in the claims.

Referring to the drawing and more particularly to Fig. 1, the reference character 1 designates the film which is caused to travel in the usual well known manner in the direction indicated by the arrow and the same is caused to pass by a light slot or slit which in this instance is customary and formed in a. plate by means of the V out therein. as indicated at 3 with the film passing on the back side of the plate 2 in contact therewith whereby it passes by the apex aperture of the V cut 3.

It is with this type of light slot or slit that the dust, dirt or other extraneous ma terial carried by the film 1 clogs up the slot or slit formed by the V 3. In Fig. 2 Ihave shown one simple arrangement embodied in my invention for overcoming this difiiculty, wherein I form the light slot plate into portions 2' and 2*, and offset laterally the plate 2 relative to plate 2.

It will be apparent that with this arrangement it is impossible for dirt, dust or the like to accumulate at the slot and of course plate 2 may be offset practically an infinitesimal distance whereby the purpose of my invention may be accomplished. To offer a clear showing thereof, however, in Fig. 2, the plate 2 has been moved a considerable distance laterally to the plate 2.

I do not desire to limit the embodiment of two separate plates 2' and 2. for it is obvious that the position 2 of a singleplate may be ofiset or dis laced by mounting or other operation to e ect the same result.

Having now set forth the objects and nature of my invention, and having shown and described the arrangements modifying the principles thereof, what I claim as new and useful and of my own invention and desire to secure by Letters Patent is:

1. Means for maintaining the light aperture of motion picture machines for recordingand reproducing sound unobstructed by dust, dirt, or the like, which consists of two members which form an aperture one member being offset from the other.

2. Means for maintaining the light aperture of motion picture machines for recording and reproducing sound unobstructed by dust, dirt, or the like which consists of two plates which form an aperture one plate being ofiset from the other and outof contact with the film.

3. Means for maintaining the light aperture of motion picture machines for recording and reproducing sound unobstructed by dust, dirt, or the like, which consists of two members which form an aperture and the member passed last by the film in its travel, being offset with respect to the other and out of contact with the film.

In testimony whereof I have hereunto set my hand on this 12th day of December A. D., 1924.

LEE on FOREST. 

